The present invention relates to a method and a device for controlling the drive unit of a motor vehicle.
German Published Patent Application No. 197 39 567 refers to the control of a drive unit, in which a plurality of setpoint assignments, some of which have contradictory effects, act on actuators. For example, the drive unit may be controlled in accordance with driver intent, setpoints of external and/or internal regulating and control functions (such as a traction control), an engine drag-torque control, a transmission control, a speed limiter, and/or an idle speed regulator. To coordinate these setpoint assignments (i.e., to determine a setpoint assignment to be implemented), a setpoint is selected from setpoints supplied through selection of maximum and minimum values. This setpoint is implemented in a momentary operating state of the drive unit through the individual control parameters of the drive unit. In an exemplary internal combustion engine according to the present invention, these control parameters may include, for example, the filling, the firing angle and/or the quantity of fuel. Conversion of the setpoints to forced values may be performed according to the origin of the setpoint assignment. For example, separate setpoint assignments may be formed for a relatively slow filling actuation path and for a relatively rapid ignition actuation path. This may limit the flexibility of selecting control parameters for implementation of the setpoint assignment.
It is believed to be advantageous in that an implementation of the setpoint variable on the basis of a continuously variable actuating time may permit a more precise assignment and implementation of intervening measures.
Through implementation of the setpoint assignment via the filling path and enabling of rapid intervention measures, such as ignition and fuel suppression, if necessary, the choice of the actuating path is made independently of the origin of the setpoint assignment. Furthermore, optimal utilization of the achievable torque via the filling path may improve overall efficiency. The optimization potential at high rotational speeds, for example, may be utilized through a choice of actuating path as a function of operating point, since the efficiency-reducing firing angle and fuel intervention measures occur only when the setpoint variable may not be reached via the filling path.